import java.util.Scanner;

public class Grade2 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入你的成绩：");
        int grade = scanner.nextInt();
        if (grade >= 90){
            System.out.println("成绩为A");
        } else if (grade >= 80) {
            System.out.println("成绩为B");
        } else if (grade >= 60) {
            System.out.println("成绩为C");
        } else if (grade >= 0 ) {
            System.out.println("成绩为D");
        }
        else {
            System.out.println("成绩无效！");
        }
    }
}
